In power converter circuits such as inverters for motor drives, solar power conversion, wind power conversion, as well as battery chargers and uninterruptable power supplies, it is typical to be using a centralized controller or microprocessor, DSP or FPGA which commands the turning-on and turning-off of the power conversion switches (power semiconductors) based on sensor feedback, setpoints and control algorithms.
The turn-on, turn-off commands are transmitted via digital lines to gate driver circuits, which more or less directly command the power switches on or off, based on the level of the digital signals (e.g. high=on /low=off).
A typical three phase inverter has six power switches, and therefore six digital lines are required between the centralized microprocessor and the gate drivers (one for each switch). For reasons of noise immunity and safety, it is further typical that the central microprocessor is galvanically isolated from the gate drivers by mean s of optical, capacitive or inductive coupling. This isolation is normally achieved at the gate driver, and is required for each line.
In addition to the gate control lines power converter circuits also typically require connections from the gate driver to the central controller processor to signal fault conditions. A total of six fault lines will be needed, if faults are to be attributable to each gate driver (and switch), resulting in a total of twelve isolated lines between the central processor and gate drivers.
This large number of digital lines and isolation barriers results in cost and complexity. Furthermore, the simple digital lines only offer very limited functionality: the commands that are transmitted to the gate-drivers have only two states (on or off), while the information returned by the gate driver is also binary (no-fault or fault). This centralized approach, besides being not optimal in terms of cost and reliability, seriously limits the role that the gate driver can play in the control of the power conversion, and prevents the system designer from fully utilizing the power conversion circuit in an intelligent and distributed fashion.
For example, the control of the power switches is limited to simple on/off commands issued by the central processor and does not allow for real time adjustments based on actual operating conditions. The feedback from the gate driver is a simple OK/not-OK and does not provide any additional information that could aid the performance of the power conversion or provide for diagnostics.
Furthermore, due to the delays from the measurement circuits to the processor and subsequently to the power switches the bandwidth of the control algorithms is inherently limited with the conventional approach.